text: The gas inside a bubble is less dense than air because it is mostly water vapor. Water vapor is a gas that is formed when water molecules evaporate. When water molecules evaporate, they escape from the liquid state and enter the gas state. In the gas state, water molecules are further apart than they are in the liquid state. This is because water molecules are attracted to each other. When they evaporate, they break away from these attractions and move further apart.
  The further apart water molecules are, the less dense they are. This is why water vapor is less dense than air. The gas inside a bubble is mostly water vapor, so it is also less dense than air.
  The density of a gas can also be affected by its temperature. As the temperature of a gas increases, the molecules of the gas move faster. This causes them to spread out and become less dense. The opposite is also true. As the temperature of a gas decreases, the molecules of the gas move slower. This causes them to bunch together and become more dense.
  The temperature of the gas inside a bubble is affected by the temperature of the water around it. The warmer the water, the warmer the gas inside the bubble. This means that the gas inside a bubble will be less dense if the water is warm than if the water is cold.